One of the surprising discoveries made by the French Concordia project (Michel Maurette/Cecile Engrand/Jean Duprat) in Antarctica in the year 2000, was porphyritic olivine (PO) micrometeorites with an abundance of iron sulfide. These rare, “barely melted” cosmic spherules have not been heated sufficiently during atmospheric entry to complete an elemental differentiation, where the iron accumulates as a dense core and the volatiles evaporate.
On the contrary, these barely melted micrometeorites are closer to how the cosmic dust particles exist in outer space, with chunks and small microspherules of iron sulfide, nickel and iron together with the magnesium silicates.
When I first started to find the same barely melted type in urban dust, I was so surprised by the unusual visual appearance that the particles were put aside. Unlike other types of micrometeorites, which I could identify visually, these particles required chemical analysis to confirm their extraterrestrial origin.
A beautiful example of this barely melted type of micrometeorite is NMM 1833, which was found on the roof of an industrial building in Vestby, outside my hometown of Oslo. NMM 1833 measures about 0.3 mm and has iron sulfide that is completely intact. Since sulfide is rapidly weathered, we know that this little speck of stardust was collected very shortly after it arrived on Earth. To me, it seems almost like a small volcanic planet!
Barely melted space gems have been the focus of a great deal of fascinating and mysterious research that may reveal many secrets of the universe, which I will discuss another time. For now, enjoy the wondrous beauty of NMM 1833 and connect with Project Stardust on Facebook, Instagram, and Twitter to stay up-to-date!